基于统一强度准则改进式的压力隧洞弹塑性应力分析

基于具有抛物线型强度包络线的统一强度准则，即对双剪双参数统一强度准则进行相应的非线性化处理，考虑了中间主应力影响，分析在渗流作用下压力隧洞弹塑性力学行为。通过分析中间主应力对压力隧洞的塑性区半径影响可知，随着中间主应力的参数的增大，塑性区半径也相应减小。通过考虑和不考虑渗流场影响的实例对比分析表明，考虑渗流场时所得塑性区半径要比不考虑时大，而且随着孔隙水压力的增大，渗流场的影响越显著。隧洞径向应力和切向应力也与中间主应力参数b和渗流场密切相关。通过与直线型统一强度准则对比分析可知，采用两种不同准则时所得结果相差较大。隧洞设计时应根据岩石强度特性合理地选择数b，为强度包络线近似于二次抛物线的围岩隧洞设计提供理论依据

Elastoplastic stress analysis of pressure tunnel based on improvement of unified strength criterion

Based on the unified strength criterion with parabolic failure envelope, the nonlinear improved expression of the two-parameter twin shear unified criterion is obtained. Elastoplastic analysis of pressure tunnels is presented by considering the seepage and intermediate principal stress. The results show that the intermediate principalstress parameter b in unified strength theory has significant effect on the radius of plastic zone. The radius of plastic zone is decreased along with the increase of the intermediate principal stress parameter b. An example is analyzed and contrasted with and without considering seepage. The radius of plastic zone with considering influence of seepage is larger than that without considering the seepage influence. The results also indicate that the parameter b and seepage have significant influences on tangential stress and radial stress. The results obtained by the original linear expression and the nonlinear improved expression of the two-parameter twin shear unified strength theory are large difference. In tunnel design, the unified strength theory parameter should be reasonably adopted according to surrounding rock material properties. So as to provide theoretical supports for tunnel design.